When throwing a cocktail party people always wonder what and how much liquor they should buy. The rule of thumb in the catering business is that on average, 10 people will consume 20 drinks at a cocktail party. If the party is a full evening fest, including dinner, then the average is 40 drinks for 10 people.  

Based on a typical 1.5 oz shot of liquor a 750 ml bottle will let you make 16 cocktails, a 1 litre bottle, 22 cocktails and a 1.5 litre bottle will make approximately 39 cocktails.

For a party of wine drinkers, plan on buying 5 bottles (750 ml) for 10 people. You should get roughly 5 servings per bottle.

For beer drinkers, buy 5 six-packs for 10 people.